Subchronic toxicity study of standardized methanolic extract of Mitragyna speciosa Korth in Sprague-Dawley Rats

Formation of multiple ion types during MALDI imaging mass spectrometry analysis of Mitragyna speciosa alkaloids in dosed rat brain tissue

Mitragyna speciosa, more commonly known as kratom, has emerged as an alternative to treat chronic pain and addiction. However, the alkaloid components of kratom, which are the major contributors to kratom's pharmaceutical properties, have not yet been fully investigated. In this study, matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry was used to map the biodistribution of three alkaloids (corynantheidine, mitragynine, and speciogynine) in rat brain tissues. The alkaloids produced three main ion types during MALDI analysis: [M + H]+, [M - H]+, and [M - 3H]+. Contrary to previous reports suggesting that the [M - H]+ and [M - 3H]+ ion types form during laser ablation, these ion types can also be produced during the MALDI matrix application process. Several strategies are proposed to accurately map the biodistribution of the alkaloids. Due to differences in the relative abundances of the ions in different biological regions of the tissue, differences in ionization efficiencies of the ions, and potential overlap of the [M - H]+ and [M - 3H]+ ion types with endogenous metabolites of the same empirical formula, a matrix that mainly produces the [M + H]+ ion type is optimal for accurate mapping of the alkaloids. Alternatively, the most abundant ion type can be mapped or the intensities of all ion types can be summed together to generate a composite image. The accuracy of each of these approaches is explored and validated.

Mitragynine inhibits hippocampus neuroplasticity and its molecular mechanism

BACKGROUND

Mitragynine (MIT), the primary indole alkaloid of kratom (Mitragyna speciosa), has been associated with addictive and cognitive decline potentials. In acute studies, MIT decreases spatial memory and inhibits hippocampal synaptic transmission in long-term potentiation (LTP). This study investigated the impacts of 14-day MIT treatment on hippocampus synaptic transmission and its possible underlying mechanisms.

METHODS

Under urethane anesthesia, field excitatory post-synaptic potentials (fEPSP) of the hippocampal CA1 region were recorded in the Sprague Dawley (SD) rats that received MIT (1, 5, and 10 mg/kg), morphine (MOR) 5 mg/kg, or vehicle (ip). The effects of the treatments on basal synaptic transmission, paired-pulse facilitation (PPF), and LTP were assessed in the CA1 region. Analysis of the brain's protein expression linked to neuroplasticity was then performed using a western blot.

RESULTS

The baseline synaptic transmission's amplitude was drastically decreased by MIT at 5 and 10 mg/kg doses, although the PPF ratio before TBS remained unchanged, the PPF ratio after TBS was significantly reduced by MIT (10 mg/kg). Strong and persistent inhibition of LTP was generated in the CA1 region by MIT (5 and 10 mg/kg) doses; this effect was not seen in MIT (1 mg/kg) treated rats. In contrast to MIT (1 mg/kg), MIT (5 and 10 mg/kg) significantly raised the extracellular glutamate levels. After exposure to MIT, GluR-1 receptor expression remained unaltered. However, NMDAε2 receptor expression was markedly downregulated. The expression of pCaMKII, pERK, pCREB, BDNF, synaptophysin, PSD-95, Delta fosB, and CDK-5 was significantly downregulated in response to MIT (5 and 10 mg/kg) exposure, while MOR (5 mg/kg) significantly raised synaptophysin and Delta fosB expression.

CONCLUSION

Findings from this work reveal that a smaller dose of MIT (1 mg/kg) poses no risk to hippocampal synaptic transmission. Alteration in neuroplasticity-associated proteins may be a molecular mechanism for MIT (5 and 10 mg/kg)-induced LTP disruption and cognitive impairments. Data from this work posit that MIT acted differently from MOR on neuroplasticity and its underlying mechanisms.

Cardiovascular health in kratom users; a narrative review

BACKGROUND

Kratom, also known as Mitragyna speciosa, is a plant that originates in Southeast Asia and possesses unique pharmacological characteristics. It is commonly consumed in the form of tea made by boiling the leaves or using the leaves to create the powder. According to its pain-relieving effects, the prevalence of kratom use around the world has increased, which has various implications for healthcare providers. Mitragynine is a well-known active compound in kratom.

OBJECTIVE

This review aims to provide a comprehensive perspective on the cardiovascular effects of mitragynine and its potential cardiotoxicity through the literature.

METHOD

Authors searched PubMed, Scopus, and Google Scholar databases using appropriate search strategies for each database. After the screening, all relevant studies were included.

RESULTS

Although kratom may have the potential for therapeutic benefits, it has been associated with multi-organ damage and cardiac toxicity in some cases. According to the available data, tachycardia and hypertension are the most common adverse effects. Other possible cardiovascular effects include atherosclerosis, ventricular arrhythmia, cardiomyopathy, dose-dependent prolonged QTc interval, myocarditis, cardiomegaly, and cardiopulmonary arrest.

CONCLUSION

While prior research has indicated the possible negative effects of mitragynine overdose on the cardiovascular system, there are no definitive conclusions, and additional investigations are needed.

A Critical Review of the Neuropharmacological Effects of Kratom: An Insight from the Functional Array of Identified Natural Compounds

Kratom (Mitragyna speciosa Korth. Havil) has been considered a narcotic drug for years, barred by the law in many parts of the world, while extensive research over the past few decades proves its several beneficial effects, some of which are still in ambiguity. In many countries, including Thailand, the indiscriminate use and abuse of kratom have led to the loss of life. Nonetheless, researchers have isolated almost fifty pure compounds from kratom, most of which are alkaloids. The most prevalent compounds, mitragynine and 7-hydroxy mitragynine, are reported to display agonist morphine-like effects on human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with multimodal effects at other central receptors. Mitragynine is also credited to be one of the modulatory molecules for the Keap1-Nrf2 pathway and SOD, CAT, GST, and associated genes' upregulatory cascades, leading it to play a pivotal role in neuroprotective actions while evidently causing neuronal disorders at high doses. Additionally, its anti-inflammatory, antioxidative, antibacterial, and gastroprotective effects are well-cited. In this context, this review focuses on the research gap to resolve ambiguities about the neuronal effects of kratom and demonstrate its prospects as a therapeutic target for neurological disorders associated with other pharmacological effects.

Effects of mitragynine on viability, proliferation, and migration of C6 rat glioma, SH-SY5Y human neuroblastoma, and HT22 immortalized mouse hippocampal neuron cell lines

Mitragynine (MG) is an indole alkaloid found in the extract of Mitragyna speciosa Korth native to Southeast Asia. Although MG is known for its pain-relieving and psychoactive effects, reports have suggested that it has therapeutic potential against neoplasms and psychiatric disorders. However, no evidence currently exists to support the effect of MG on brain tumors. This study aimed to investigate the antitumor effects of MG in C6 rat glioma and SH-SY5Y human neuroblastoma tumor cell lines compared with those in the non-tumor HT22 mouse hippocampal neuronal cell line. MTT assay for cell viability, clonogenic and wound healing assays for cell migration, Hoechst 33342/propidium iodide staining for nuclear morphology, and cell cycle distribution using flow cytometry were performed. MG at 125.47 μM (50 μg/ml) significantly reduced the viability of all cell lines, and the clonogenicity of C6 glioma cells began decreasing at 75.28 μM (30 μg/ml) of MG. Cell migration was inhibited in C6 and HT22 cells treated with 75.28 μM (30 μg/ml) of MG. Apoptotic nuclear condensation and fragmentation were observed in all cell lines treated with 125.47 μM (50 μg/ml) MG, whereas late-phase apoptotic cells were predominant in the group treated with 250.94 μM (100 μg/ml) of MG. The cell cycle assay results suggest that MG arrested the S phase in the C6 cell line and the G2/M phase in the HT22 cell lines. This study showed that MG induces cell death and cell cycle arrest, disrupting cell migration and reducing the clonogenicity of brain tumor cells.

Evaluation of toxicity profile of kratom (Mitragyna speciosa Korth) decoction in rats

Mitragyna speciosa Korth also known as kratom, is an herbal drug preparation for its therapeutic properties and opioid-replacement therapy. Kratom is consumed in a brewed decoction form in Malaysia and to date, no studies have characterized its chemical and toxicity profile. Thus, this study aims to evaluate kratom decoction's safety and toxicity profile after 28 days of treatment. Mitragynine content was quantified in kratom decoction and used as a marker to determine the concentration. Male and female Sprague Dawley rats were orally treated with vehicle or kratom decoction (10, 50 or 150 mg/kg) and two satellite groups were treated with vehicle and kratom decoction (150 mg/kg). Blood and organs were collected for hematology, biochemical and histopathology analysis at the end of treatment. No mortality was found after 28 days of treatment and no significant changes in body weight and hematology profile, except for low platelet count. High amounts of uric acid, AST, ALT and alkaline phosphatase were found in the biochemical analysis. Histological investigation of the heart and lungs detected no alterations except for the kidney, liver and brain tissues. In conclusion, repeated administration of kratom decoction provided some evidence of toxicity in the kidney and liver with no occurrence of mortality.

Traditional medicine consumption in postpartum for HBV-infected women enrolled in the ANRS 12345 TA PROHM study in Cambodia

In Cambodia, traditional medicine was commonly described as being used by pregnant women at two time points: one month before birth and during early postpartum. The present study aims to describe traditional medicine consumption during postpartum phase for women enrolled in the TA PROHM study and to investigate the possible association between traditional medicine consumption and acute liver toxicity. An ethnobotanical survey was conducted in 2 groups of HBV-infected pregnant women (with and without postpartum hepatocellular injury) enrolled in the study. Hepatocellular injury was defined by having Alanine Aminotransferase (ALT) > 2.5 times the Upper Limit of Normal (ULN = 40 U/L) at the 6th week postpartum visit. Interviews were done using a standardized questionnaire. Plant samples were collected and later identified by two traditional healers. Chi-square test was used to find the association between hepatocellular injury and traditional medicine consumption or a specific plant species. In total, 75 women were enrolled and 52 (69.3%) used at least one traditional remedy composed of 123 different plants and 12 alcoholic macerations of porcupine stomach. Orally consuming at least one remedy with alcohol was significantly associated with hepatocellular injury (33% vs 13%, p = 0.034). Among the 123 plants species identified, four were found to be associated with hepatocellular injury, namely Amphineurion marginatum (Roxb.) D.J.Middleton [Apocynaceae] (p = 0.022), Selaginella tamariscina (P.Beauv.) Spring [Selaginellaceae] (p = 0.048), Mitragyna speciosa Korth. [Rubiaceae] (p = 0.099) and Tetracera indica (Christm. & Panz.) Merr. [Dilleniaceae] (p = 0.079). Consumption of traditional medicine in postpartum is a common practice for women enrolled in the TA PROHM study. Alcohol-based remedies may exacerbate the risk of acute hepatocellular injury in HBV-infected women already exposed to immune restoration. The complex mixtures of herbs need to be further evaluated by in vitro and in vivo studies.

Controversial usages of kratom (Mitragyna speciosa): For good or for evil

Kratom (Mitragyna speciosa) is a plant that grows well in tropical climates such as in Southeast Asia. Traditionally, people discovered it possessed a stimulating effect that relieved tiredness. Furthermore, it contains analgesic and medicinal properties for the treatment of pain, diarrhea, muscle discomfort, and blood pressure and to enhance stamina. Nevertheless, long term or regular consumption of kratom leads to addiction. This is because the main alkaloid of kratom, mitragynine, binds to opioid receptors and exerts a euphoric effect similar to that of morphine, which may lead to death. Due to this reason, kratom has been listed as a regulated substance in many countries including the United States, Thailand, Malaysia, Bhutan, Finland, Lithuania, Denmark, Poland, Sweden, Australia, and Myanmar. Usages of kratom carry two pharmacological effects depending on dosage. Low-dose kratom exerts a stimulating effect that refreshes the user. High-dose kratom exerts sedative effects that can lead to addiction similar to that of morphine. Despite the euphoric effect of kratom, the beneficial values of kratom to human health is indisputable. Therefore, a complete banning of kratom may cause a loss to pharmaceutical industry. Rather, a controlled or selective usage of kratom will be a better choice.

Kratom as an opioid alternative: harm, or harm reduction? A systematic review of literature

Background: Kratom (Mitragyna speciosa Korth.) products are increasingly endorsed for self-management of multiple ailments, including as opioid substitution. The FDA has expressed that there is no evidence to indicate that this botanical is safe or effective for any medical use.Objective: We systematically review the current state of the literature concerning the impact of kratom and its alkaloids in all paradigms that involve opioids.Methods: A keyword search of online literature databases identified 16 preclinical studies, 25 case reports, and 10 observational studies meeting our pre-selected criteria.Results: All rodent models support alkaloids' action on opioid receptors, translating in their ability to mitigate opioid withdrawal. Some studies found mitragynine (MG) to have less reinforcing properties than morphine, and possessing tolerance-sparing properties when coadministered with morphine. Two studies that assessed 7-hydroxymitragynine (7OHMG) found it to substitute for morphine with potential for tolerance and dependence. Aside from addiction development, case reports outline a variety of confounding toxicities. Ten surveys of users, some conducted with assistance from pro-kratom lobbying organizations, find a high self-reported efficacy as an opioid substitute, with minimal reported adverse effects.Conclusion: With no reported controlled human clinical trials, in the light of rising concerns surrounding kratom's liabilities, there is insufficient evidence to allow any conclusions to be drawn. Case reports and observational studies carry significant bias toward harm and efficacy, respectively. Existing animal studies are heterogeneous in methodology and ultimately findings, with concern for interspecies variability and human translatability. Further research should investigate the safety and efficacy of using kratom alkaloids as opioid substitutes.

Antimicrobial Activity of Some Plant Extracts and Their Applications in Homemade Tomato Paste and Pasteurized Cow Milk as Natural Preservatives

Synthetic chemical preservatives are widely used in the food industry to delay the deterioration caused by microbial growth, enzyme activities and oxidation reactions. The last few decades have witnessed marked interest in finding natural food preservatives due to the potential health damage of synthetic preservatives; consumers have become skeptical of consuming foods containing these additives. Polyphenols used as natural preservatives that can be extracted from fruits, vegetables, herbs and spices provide the best alternative for partial or complete replacement of their synthetic analogues. The present study’s emphasis was on employing different plant extracts to be efficiently used as antimicrobial agents for developing replacements for the synthetic chemical additives in food products. The study also investigated the antimicrobial potentialities of five medicinal plants, widely used in Egypt (sumac, tamarind, rosemary, roselle and lemon) against six microbial markers (E. coli, P. aeruginosae, B. subtilis, S. aureus, Penicillium sp. and A. niger.). Sumac extracts showed the best activity against all tested microorganisms, producing the widest inhibition zones ranging from 14 to 45 mm, followed by tamarind and roselle extracts, with inhibition zones ranging from 8–36 and 8–34 mm, respectively. On the other hand, extracts of rosemary and lemon showed variable antimicrobial activity. All extracts from all tested plants were less active against fungal species than bacterial species. In all cases, the organic extracts (80% methanol, 80% ethanol) showed the same or greater activity than the aqueous extracts. In addition, the methanolic extracts showed the strongest and broadest spectrum. The most sensitive strain to plant extracts was B. subtilis, while the most resistant strain was P. aeruginosae. The MIC and MBC or MFC values of methanolic extracts were assayed using the broth dilution method. Sumac extract showed the best activity against all tested microorganisms with the lowest values of MIC and MBC or MFC (from 0.260 to 0.877 and 0.310 to 1.316 mg/mL, respectively, for bacteria, and from 1.975 to 2.5 and 2.5 to 4.444 mg/mL, respectively, for fungi). Interestingly, the tested extracts inhibited microbial growth in tomato paste and pasteurized cow milk for a long storage period (increase shelf life) as compared to the control samples. In conclusion, herbal and spice extracts could be successfully applied as natural antimicrobials for the elimination of food borne microbes and pathogen growth.

Assessment of the possible health risks associated with the consumption of botanical preparations of Mitragyna speciosa (kratom)

The current report summarises the work performed in the context of the European Food Risk Assessment Fellowship Programme (EU‐FORA), which included the evaluation of health risks associated with the consumption of botanical preparations of Mitragyna speciosa (kratom). Mitragyna speciosa is a tree native to Southeast Asia, where its leaves and preparations of the leaves have been used for centuries, among others, as a stimulant or as a traditional herbal medicine. Preparations of the plant have recently gained increasing popularity in other parts of the world, and are presently also accessible via online platforms, e.g. as food supplements. Kratom has been considered a botanical of possible health concern by the FDA and EFSA, which together with its increasing popularity, makes kratom a subject of international concern. Major alkaloids of the plant, mitragynine and 7‐hydroxymitragynine, are agonists of the μ‐opioid human receptor and are assumed to be mainly responsible for its psychoactive effects. The aim of the present project was to conduct an assessment of potential health risks associated with oral use of kratom‐based preparations. The animal and human data that were evaluated in the course of the current assessment indicate that kratom consumption has the potential to not only lead to adverse neurological effects, including addiction and withdrawal syndrome, but also to elicit distinct organ toxicity with respect to e. g. liver and kidney as target organs. Nevertheless, actual risk characterisation is impeded by considerable uncertainties. Such uncertainties, based on the variability in composition of kratom preparations, insufficient information on dose–response relationships and on limited data on long‐term use effects, currently do not allow the derivation of distinct health based guidance values for kratom/kratom preparations. Further information from well‐designed studies, conducted with kratom preparations that have been clearly defined with respect to their composition, would be required to enable a more refined risk assessment of this botanical.

A Case of Hyperkalemia Induced by Kratom (Mitragyna speciosa)

Kratom (Mitragyna speciosa), a tree found abundantly in Southeast Asia, has been used for centuries because of its opioid-like properties. In the last 20 years, it has gained popularity in the United States of America due to its easy availability and effects on pain control. However, different types of toxicity from kratom use have been reported in the literature. Here, we present a case of kratom-induced hyperkalemia in a 61-year-old patient with no significant past medical history. His laboratory work-up excluded other etiologies, and his potassium level eventually normalized after the discontinuation of kratom. Although reasonable data exist on kratom effects on the nervous and cardiovascular systems, the magnitude of its effect on potassium homeostasis and whether it is kidney mediated or not is not well recognized.

The Chemical and Pharmacological Properties of Mitragynine and Its Diastereomers: An Insight Review

Mitragynine, is a naturally occurring indole alkaloid that can be isolated from the leaves of a psychoactive medicinal plant. Mitragyna speciosa, also known as kratom, is found to possess promising analgesic effects on mediating the opioid receptors such as µ (MOR), δ (DOR), and κ (KOR). This alkaloid has therapeutic potential for pain management as it has limited adverse effect compared to a classical opioid, morphine. Mitragynine is frequently regarded to behave like an opioid but possesses milder withdrawal symptoms. The use of this alkaloid as the source of an analgesic candidate has been proven through comprehensive preclinical and clinical studies. The present data have shown that mitragynine is able to bind to opioid receptors, particularly MOR, to exhibit the analgesic effect. Moreover, the chemical and pharmacological aspects of mitragynine and its diastereomers, speciogynine, speciociliatine, and mitraciliatine, are discussed. It is interesting to know how the difference in stereochemical configuration could lead to the difference in the bioactivity of the respective compounds. Hence, in this review, the updated pharmacological and toxicological properties of mitragynine and its diastereomers are discussed to render a comprehensive understanding of the pharmacological properties of mitragynine and its diastereomers based on their structure–activity relationship study.

Mitragyna Species as Pharmacological Agents: From Abuse to Promising Pharmaceutical Products

Mitragyna is a genus belonging to the Rubiaceae family and is a plant endemic to Asia and Africa. Traditionally, the plants of this genus were used by local people to treat some diseases from generation to generation. Mitragyna speciosa (Korth.) Havil. is a controversial plant from this genus, known under the trading name “kratom”, and contains more than 40 different types of alkaloids. Mitragynine and 7-hydroxymitragynine have agonist morphine-like effects on opioid receptors. Globally, Mitragyna plants have high economic value. However, regulations regarding the circulation and use of these commodities vary in several countries around the world. This review article aims to comprehensively examine Mitragyna plants (mainly M. speciosa) as potential pharmacological agents by looking at various aspects of the plants. A literature search was performed and information collected using electronic databases including Scopus, ScienceDirect, PubMed, directory open access journal (DOAJ), and Google Scholar in early 2020 to mid-2021. This narrative review highlights some aspects of this genus, including historical background and botanical origins, habitat, cultivation, its use in traditional medicine, phytochemistry, pharmacology and toxicity, abuse and addiction, legal issues, and the potential of Mitragyna species as pharmaceutical products.

Mitragynine improves cognitive performance in morphine-withdrawn rats

RATIONALE

The treatment of opiate addiction is an unmet medical need. Repeated exposure to opiates disrupts cognitive performance. Opioid substitution therapy, with, e.g., methadone, may further exacerbate the cognitive deficits. Growing evidence suggests that mitragynine, the primary alkaloid from the Kratom (Mitragyna speciosa) leaves, may serve as a promising alternative therapy for opiate addiction. However, the knowledge of its health consequences is still limited.

OBJECTIVES

We aimed to examine the cognitive effects of mitragynine substitution in morphine-withdrawn rats. Furthermore, we asked whether neuronal addiction markers like the brain-derived neurotrophic factor (BDNF) and Ca²⁺/calmodulin-dependent kinase II alpha (αCaMKII) might mediate the observed effects.

METHODS

Male Sprague-Dawley rats were given morphine at escalating doses before treatment was discontinued to induce a spontaneous morphine withdrawal. Then, vehicle or mitragynine (5 mg/kg, 15 mg/kg, or 30 mg/kg) substitution was given for 3 days. A vehicle-treated group was used as a control. Withdrawal signs were scored after 24 h, 48 h, and 72 h, while novel object recognition (NOR) and attentional set-shifting (ASST) were tested during the substitution period.

RESULTS

Discontinuation of morphine significantly induced morphine withdrawal signs and cognitive deficit in the ASST. The substitution with mitragynine was able to alleviate the withdrawal signs. Mitragynine did not affect the recognition memory in the NOR but significantly improved the reversal learning deficit in the morphine-withdrawn rats.

CONCLUSIONS

These data support the idea that mitragynine could be used as safe medication therapy to treat opiate addiction with beneficial effects on cognitive deficits.

A systematic review of (pre)clinical studies on the therapeutic potential and safety profile of kratom in humans

INTRODUCTION

Kratom (Mitragyna speciosa) is a tropical plant traditionally used as an ethnomedicinal remedy for several conditions in South East Asia. Despite the increased interest in its therapeutical benefits in Western countries, little scientific evidence is available to support such claims, and existing data remain limited to kratom's chronic consumption.

OBJECTIVE

Our study aims to investigate (pre)clinical evidence on the efficacy of kratom as a therapeutic aid and its safety profile in humans.

METHODS

A systematic literature search using PubMed and the Medline database was conducted between April and November 2020.

RESULTS

Both preclinical (N = 57) and clinical (N = 18) studies emerged from our search. Preclinical data indicated a therapeutic value in terms of acute/chronic pain (N = 23), morphine/ethanol withdrawal, and dependence (N = 14), among other medical conditions (N = 26). Clinical data included interventional studies (N = 2) reporting reduced pain sensitivity, and observational studies (N = 9) describing the association between kratom's chronic (daily/frequent) use and safety issues, in terms of health consequences (e.g., learning impairment, high cholesterol level, dependence/withdrawal).

CONCLUSIONS

Although the initial (pre)clinical evidence on kratom's therapeutic potential and its safety profile in humans is encouraging, further validation in large, controlled clinical trials is required.

Kratom (Mitragyna Speciosa) Liver Injury: A Comprehensive Review

Kratom (Mitragyna speciosa) leaves contain the mu opioid partial agonists mitragynine and 7-hydroxymitragynine. The US Drug Enforcement Agency considers it a 'drug of concern', and the US FDA is reviewing kratom, but there is a paucity of information regarding health effects. Liver injury is often cited as a potential health consequence, however the same few case reports are repeatedly referenced, without a broader context. Furthermore, reports have largely lacked standardized causality assessment methods. The objective is to evaluate causality in kratom liver injury, through a comprehensive scoping review of human cases, and by reviewing epidemiologic, animal, and mechanistic reports that relate to kratom liver injury. Hepatotoxicity causality was systematically examined using the Roussel Uclaf Causality Assessment Method (RUCAM) for case reports. Biopsy findings, potential pathophysiologic mechanisms, and management options are discussed. This review identified 26 case reports and abstracts, in addition to 7 cases reported from the Drug-Induced Liver Injury Network, 25 in FDA databases, and 27 in internet user forums. Latency periods to symptom onset had a median of 20.6 days and mean of 21 days (range 2-49). Common presenting signs and symptoms were abdominal discomfort, jaundice, pruritis, and dark urine. Histologic findings were predominantly cholestatic, although, biochemically, the condition was heterogenous or mixed; the median R ratio was 3.4 and the mean was 4.6 (range 0.24-10.4). Kratom likely causes liver injury based on the totality of low-quality human evidence, and, in the context of epidemiologic, animal, and mechanistic studies. It remains unclear which subgroups of users are at heightened risk.

Kratom-Pharmacology, Clinical Implications, and Outlook: A Comprehensive Review

Kratom, or Mitragyna, is a tropical plant indigenous to Southeast Asia, with unique pharmacological properties. It is commonly consumed by preparing the leaves into decoction or tea, or by grinding them into a powder. Recent evidence has revealed that kratom has physiological effects similar to opioids, including pain relief and euphoria, as well as stimulant properties, which together raise potential concern for dependence and addiction. Moreover, growing evidence suggests that the prevalence of kratom use is increasing in many parts of the world, raising important considerations for healthcare providers. This manuscript will discuss the most current epidemiology, pharmacology, toxicity, and management related to kratom, while seeking to provide a contemporary perspective on the issue and its role in the greater context of the opioid epidemic.

Mitragynine, an euphoric compound inhibits hERG1a/1b channel current and upregulates the complexation of hERG1a-Hsp90 in HEK293-hERG1a/1b cells

Mitragyna speciosa Korth (M. speciosa) has been widely used as a recreational product, however, there are growing concerns on the abuse potentials and toxicity of the plant. Several poisoning and fatal cases involving kratom and mitragynine have been reported but the underlying causes remain unclear. The human ether-a-go-go-related gene 1 (hERG1) encodes the pore-forming subunit underlying cardiac rapidly delayed rectifier potassium current (I_Kr). Pharmacological blockade of the I_Kr can cause acquired long QT syndrome, leading to lethal cardiac arrhythmias. This study aims to elucidate the mechanisms of mitragynine-induced inhibition on hERG1a/1b current. Electrophysiology experiments were carried out using Port-a-Patch system. Quantitative RT-PCR, Western blot analysis, immunofluorescence and co-immunoprecipitation methods were used to determine the effects of mitragynine on hERG1a/1b expression and hERG1-cytosolic chaperones interaction. Mitragynine was found to inhibit the I_Kr current with an IC₅₀ value of 332.70 nM. It causes a significant reduction of the fully-glycosylated (fg) hERG1a protein expression but upregulates both core-glycosylated (cg) expression and hERG1a-Hsp90 complexes, suggesting possible impaired hERG1a trafficking. In conclusion, mitragynine inhibits hERG1a/1b current through direct channel blockade at lower concentration, but at higher concentration, it upregulates the complexation of hERG1a-Hsp90 which may be inhibitory towards channel trafficking.

Mitragyna speciosa: Clinical, Toxicological Aspects and Analysis in Biological and Non-Biological Samples

The abuse of psychotropic substances is a well-known phenomenon, and many of them are usually associated with ancestral traditions and home remedies. This is the case of Mitragyna speciosa (kratom), a tropical tree used to improve work performance and to withstand great heat. According to several published studies, the main reasons for kratom consumption involve improving sexual performance and endurance, but also social and recreational uses for the feeling of happiness and euphoria; it is also used for medical purposes as a pain reliever, and in the treatment of diarrhea, fever, diabetes, and hypertension. However, this plant has gained more popularity amongst young people over the last years. Since it is available on the internet for purchase, its use is now widely as a drug of abuse, namely as a new psychoactive substance, being a cheaper alternative to opioids that does not require medical prescription in most countries. According to internet surveys by the European Monitoring Centre for Drugs and Drug Addiction in 2008 and 2011, kratom was one of the most widely supplied new psychoactive substances. The composition of kratom is complex; in fact, more than 40 different alkaloids have been identified in Mitragyna speciosa so far, the major constituent being mitragynine, which is exclusive to this plant. Besides mitragynine, alkaloids such as corynantheidine and 7-hydroxamitragynine also present pharmacological effects, a feature that may be attributed to the remaining constituents as well. The main goal of this review is not only to understand the origin, chemistry, consumption, and analytical methodologies for analysis and mechanism of action, but also the use of secondary metabolites of kratom as therapeutic drugs and the assessment of potential risks associated with its consumption, in order to aid health professionals, toxicologists, and police authorities in cases where this plant is present.

The medicinal chemistry and neuropharmacology of kratom: A preliminary discussion of a promising medicinal plant and analysis of its potential for abuse

The leaves of Mitragyna speciosa (commonly known as kratom), a tree endogenous to parts of Southeast Asia, have been used traditionally for their stimulant, mood-elevating, and analgesic effects and have recently attracted significant attention due to increased use in Western cultures as an alternative medicine. The plant's active alkaloid constituents, mitragynine and 7-hydroxymitragynine, have been shown to modulate opioid receptors, acting as partial agonists at mu-opioid receptors and competitive antagonists at kappa- and delta-opioid receptors. Furthermore, both alkaloids are G protein-biased agonists of the mu-opioid receptor and therefore, may induce less respiratory depression than classical opioid agonists. The Mitragyna alkaloids also appear to exert diverse activities at other brain receptors (including adrenergic, serotonergic, and dopaminergic receptors), which may explain the complex pharmacological profile of raw kratom extracts, although characterization of effects at these other targets remains extremely limited. Through allometric scaling, doses of pure mitragynine and 7-hydroxymitragynine used in animal studies can be related to single doses of raw kratom plant commonly consumed by humans, permitting preliminary interpretation of expected behavioral and physiological effects in man based on this preclinical data and comparison to both anecdotal human experience and multiple epidemiological surveys. Kratom exposure alone has not been causally associated with human fatalities to date. However, further research is needed to clarify the complex mechanism of action of the Mitragyna alkaloids and unlock their full therapeutic potential. This article is part of the Special Issue entitled 'Designer Drugs and Legal Highs.'

Neurobiology of Kratom and its main alkaloid mitragynine

Kratom or its main alkaloid, mitragynine is derived from the plant Mitragyna speciosa Korth which is indigenous to Southeast Asian countries. This substance has become widely available in other countries like Europe and United States due to its opium- and coca-like effects. In this article, we have reviewed available reports on mitragynine and other M. speciosa extracts. M. speciosa has been proven to have a rewarding effect and is effective in alleviating the morphine and ethanol withdrawal effects. However, studies in human revealed that prolonged consumption of this plant led to dependence and tolerance while cessation caused a series of aversive withdrawal symptoms. Findings also showed that M. speciosa extracts possess antinociceptive, anti-inflammatory, anti-depressant, and muscle relaxant properties. Available evidence further supports the adverse effects of M. speciosa preparations, mitragynine on cognition. Pharmacological activities are mainly mediated via opioid receptors as well as neuronal Ca²⁺ channels, expression of cAMP and CREB protein and via descending monoaminergic system. Physicochemical properties of mitragynine have been documented which may further explain the variation in pharmacological responses. In summary, current researchs on its main indole alkaloid, mitragynine suggest both therapeutic and addictive potential but further research on its molecular effects is needed.